Light emitting device and manufacturing method thereof

ABSTRACT

The light-emitting device has a plurality of light-emitting elements that is mounted on one or more wiring patterns on a substrate. A new light-emitting element that replaces a defective element is mounted on the same wiring pattern on which the defective element is mounted. The defective element or a trace that remains alter removal of the defective element is sealed by a same sealing member by which the new light-emitting element is sealed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to a light-emitting device and a manufacturing method thereof.

2. Description of the Related Art

Conventionally, light-emitting devices in which a plurality of light-emitting elements are mounted on a substrate have been proposed (refer to Japanese Patent Application Publication No. 2005-322937).

The conventional light-emitting device, however, has to be scrapped in a case that one of the plurality of light-emitting elements is defective.

SUMMARY OF THE INVENTION

In one embodiment, a light-emitting device is provided in which a plurality of light-emitting elements is mounted on one or more wiring patterns on a substrate. The plurality of light-emitting elements includes a new light-emitting element that replaces a defective element and the new light-emitting element is mounted on the same wiring pattern on which the defective element is or was mounted. The defective element or a trace of the defective element that remains after removal of the defective element is sealed by a same sealing member by which the new light-emitting element is sealed.

Another aspect of the invention relates to a method for manufacturing a light-emitting device. The method includes mounting a plurality of light-emitting elements on one or more wiring patterns on a substrate, mounting a new light-emitting element that replaces a defective element of the plurality of light-emitting elements on the same wiring pattern on which the defective element is or was mounted, sealing the new element with a sealing member, and sealing the detective element or a trace of the defective element that remains after removal of the defective element by a same sealing member by which the new light-emitting element is sealed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are diagrams illustrating the schematic configuration of a light-emitting device according to an embodiment;

FIGS. 2A, 3A AND 4A form a set of diagrams illustrating a schematic process of a method for manufacturing a light-emitting device according to an embodiment;

FIGS. 2B, 3B and 4B form a set. of diagrams illustrating a schematic process of a method for manufacturing a light-emitting device according to an embodiment;

FIGS. 2C, 3C and 4C form a set of diagrams illustrating a schematic process of a method for manufacturing a light-emitting device according to an embodiment;

FIGS. 2D, 3D and 4D form a set of diagrams illustrating a schematic process of a method for manufacturing a light-emitting device according to an embodiment; and

FIGS. 2E, 3E and 4E form a set of diagrams illustrating a schematic process of a method for manufacturing a light-emitting device according to an embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference to the accompanying drawings.

[Light-Emitting Device]

FIGS. 1A-1C are diagrams illustrating the schematic configuration of a light-emitting device according to an embodiment. FIG. 1A is a perspective-view diagram. FIG. 1B is a diagram illustrating a cross-section A-A in FIG. 1A, and FIG. 1C is a diagram illustrating a cross-section B-B in FIG. 1A.

As illustrated in FIGS. 1A-1C, a light-emitting device 1 according to an embodiment is a light-emitting device in which a plurality of light-emitting elements 6 e, 6 b, 6 f, 6 d are mounted on one or more wiring patterns 4 on a substrate 2.

The light-emitting elements 6 e, 6 f among the plurality of light-emitting elements 6 e, 6 b, 6 f, 6 d are new light-emitting elements that replace defective elements 6 a, 6 c. The defective element 6 a is removed from the substrate 2, and does not appear in FIGS. 1A-1C.

Among the defective elements 6 a, 6 c, the defective element 6 a is a defective element that causes an electrical short-circuit, and is removed from the substrate 2. On the other hand, the defective element 6 c is a defective element that is not electrically connected to the circuit, and is not removed from the substrate 2.

A trace 10 that remains after removal of the defective element. 6 a is covered by a reflective member 12 to make up for the drop in reflectance this is caused by the removal of the defective element 6 a. A die bonding mark and/or a die bonding material residue are examples of the trace 10. The defective element 6 c is covered by the reflective member 12 to make up for the drop in reflectance that is caused by the presence of the defective element 6 c.

The defective element 6 a is removed and the defective element 6 c is covered by the reflective member 12. Therefore, the defective elements 6 a, 6 c do not appear on the light-emitting surface side of the light-emitting device 1.

The new light-emitting elements 6 e, 6 f are mounted on the same wiring pattern 4 on which the defective elements 6 a, 6 c are mounted, adjacent to the sites at which the defective elements 6 a, 6 c are mounted. That is, the new light-emitting elements 6 e, 6 f are mounted adjacent to the sites at which the light-emitting elements are originally intended to foe mounted. The trace 10 that remains after removal of the defective element 6 a is sealed by the same sealing member 8 a by which the new light-emitting element 6 e is sealed. The defective element 6 c is sealed by the same sealing member 8 c by which the new light-emitting element 6 f is sealed.

Therefore, the embodiment allows preventing the emission, points of new light-emitting elements 6 e, 6 f from being offset from the emission points of the defective elements 6 a, 6 c (i.e. allows maintaining the positions of the initial emission points as much as possible), and allows mitigating the influence on optical performance derived from providing a new light-emitting element instead of a defective element such as the drop of output of the light-emitting device 1 in which a lens-like sealing member 8 is provided.

Therefore, according to the embodiment, it becomes possible to use the light-emitting device 1 that was conventionally scrapped by reason of that a plurality of light-emitting elements include a defective element.

When the new light-emitting elements 6 e, of are mounted on the same wiring pattern 4 on which the defective elements 6 a, 6 c are mounted, there is no longer a need to provide, newly or beforehand, a spare wiring pattern 4 for mounting the new light-emitting elements 6 e, 6 f. Accordingly, it becomes possible to simplify the wiring pattern 4, and to provide a small light-emitting device at a low cost and with a high degree of design freedom.

Members of the light-emitting device 1 according to the embodiment will be described below.

(Substrate 2)

Various members can be appropriately used as the substrate 2. For example, a member in which paper is impregnated with a phenolic or epoxy resin or a member in which a band-like resin or metal is used as a base are examples of the substrate 2.

An insulating material or a conductive member such as an elongate tape-like copper foil or aluminum foil covered by an insulating material are examples of the substrate 2. An insulating resin such as polyimide, PET, PEN or the like is an example of the insulating material.

The thickness of the substrate is not particularly limited. A range from about 10 μm to 2 mm is an example of the thickness of the substrate.

The shape and size of the area of the substrate 2 are not particularly limited. For example, plate-like, sheet-like (tape-like, film-like), rod-like, pipe-like, wire-like, band-like shapes and the like are examples of the shape. The light-emitting device 1 can be produced in accordance with a roll-to-roll method when a flexible band-like substrate is used as the substrate 2.

(Wiring Pattern 4)

A metal such as copper, aluminum, nickel, iron, gold, silver or the like, or an alloy thereof; or plating, a conductive paste, a conductive ink comprising the foregoing metals; or solder formed out of tin, silver, copper, gold, bismuth, zinc, lead or the like are examples of the one or more wiring patterns 4.

Preferably, the one or more wiring patterns 4 is/are provided in such, a manner that the new light-emitting elements 6 e, 6 f can be mounted adjacent to the detective elements 6 a, 6 c. In this case, the sites of the new light-emitting elements 6 e, of become closer to the sites of the defective elements 6 a, 6 c, and the defective element 6 c and/or the trace 10 that arises after removal of a defective element 6 a is readily sealed by the same sealing members 8 a, 8 c by which the new light-emitting elements 6 e, 6 f are sealed.

On the one or more wiring patterns 4, a pattern for self-alignment that is used during mounting of the light-emitting element and/or another positioning patterns may be provided. In this case, the new light-emitting elements 6 e, 6 f that replace the defective elements 6 a, 6 c and the original light-emitting element 6 a, 6 b, 6 c, 6 d are readily mounted. Cutouts or protrusions having a width identical or close to a width of the electrodes of the light-emitting elements are examples of the pattern tor self-alignment.

(Light-Emitting Elements 6 a to 6 f)

Various light-emitting diodes such as surface mounted-type LEDs, LED chips, chip-size package LEDs or the like can be used as the light-emitting elements 6 a to 6 f. When LED chips are used, costs can be particularly reduced.

The light-emitting elements 6 a to 6 f can be electrically connected to the one or more wiring patterns 4 by various methods such as flip-chip mounting using bumps or solder and wire bonding using wires.

Unlike by mounting using solder, it is usually difficult to mount light-emitting elements over a plurality of times at the same site by flip-chip-type ultrasonic mounting using bumps.

However, according to the light-emitting device 1 of the embodiment, the new light-emitting elements 6 e, 6 f are mounted at the sites that ate different from the sites at which the defective elements 6 a, 6 c are mounted, and then the defective element 6 c and the trace 10 that arises after removal of a defective element 6 a are readily sealed by the same sealing members 8 a, 8 c by which the new light-emitting elements 6 e, 6 f are sealed.

In the embodiment, therefore, the new light-emitting elements 6 e, 6 f that replace the defective elements 6 a, 6 c can be easily mounted also by flip-chip-type ultrasonic mounting using bumps.

Various light-emitting elements that do not allow attaining a desired goal are regarded as the detective elements. For example, light-emitting elements that exhibit a characteristic such as voltage rise, voltage drop, or drop in brightness are examples of the defective elements.

Depending on the state of the defect, the defective element may be removed from the substrate 2, or may be left mounted on the substrate 2 without being removed. For example, in a case that a defective element is a defective element that is not electrically connected to the one or more wiring patterns 4 on account of an electric junction defect or the like (open failure), the influence on electric performance is small even if a new light-emitting element that replaces the defective element is mounted without removal of the defective element. Accordingly, the defective element need not be removed in this case (refer to light-emitting element 6 c in FIGS. 1A and 1C). In a case that the defective elements are not removed, no process is required for removing the defective elements, and the number of processes can be reduced.

(Sealing Members 8 a, 8 b, 8 c, 8 d)

A transparent resin such as epoxy resin, silicone resin or modified types thereof can be used as the sealing members 8 a, 8 b, 8 c, 8 d.

Preferably, the sealing members 8 a, 8 b, 8 c, 8 d include a wavelength conversion member such as phosphors quantum dots, a light diffusion member that diffuses a light and the like.

For example, a phosphor such as an oxide-based, sulfide-based or nitride-based phosphor can be used as the wavelength conversion member. In a case that a gallium nitride-based light-emitting element that emits blue light is used as the light-emitting elements, it is preferable to use, singly or in combination, a YAG-based or LAG-based phosphor that emits yellow to green light upon absorption of blue light, a SiAlON-based phosphor that emits green, light, or a SCASN-based or CASN-based phosphor that emits red light.

In particular, a combination of a SiAlON-based phosphor and a SCASN phosphor is preferably used as the wavelength conversion member in a light-emitting device that is used in a display device such as a liquid crystal display or a backlight of a television set. A combination of a YAG-based or LAG-based phosphor and a SCASN-based or CASN-based phosphor is preferably used as the wavelength conversion member in a light-emitting device for illumination applications.

For example, barium sulfate, titanium oxide, aluminum, oxide or silicon oxide can be used as a light scattering member.

The abovementioned wavelength conversion member and light scattering member can be included in a member that is different from the sealing members 8 a, 8 b, 8 c, 8 d. For example, members provided at a distance from the sealing members 8 a, 8 b, 8 c, 8 d in the light-emitting device 1 or members that are provided separately from the light-emitting device 1 (for example, covers, sheets and the like that are attached to an illumination device or a liquid crystal display) are examples of those different members.

When the wavelength conversion member is provided in the sealing members 8 a, 8 b, 8 c, 8 d, the light emitted by the light-emitting elements strikes on the wavelength conversion member and then is diffused. In this case, by covering the die bonding mark, defective element and so on in the sealing members 8 a, 8 b, 8 c, 8 d with the reflective member 12, the influence on emission is reduced. On the other hand, in a case that the wavelength conversion member is not provided in the sealing members 8 a, 8 b, 8 c, 8 d (i.e. in a case that the wavelength conversion member is provided in a member that is provided spaced apart from the sealing members 8 a, 8 b, 8 c, 8 d, or in a member that is provided separately from the light-emitting device 1), the influence on light emission can be reduced by covering at least part of the die bonding mark, the defective elements and so on.

Preferably, the shape of the sealing members 8 a, 83 a, 8 c, 8 d is a shape that has a lens effect. In this case, luminance can be enhanced.

In the embodiment, an example has been illustrated wherein each sealing member 8 a, 8 b, 8 c, 8 d seals one respective light-emitting element 6 e, 6 b, 6 f, 6 d. However, two or more light-emitting elements can be sealed collectively by one sealing member. In this case, two or more light-emitting elements may be sealed by one sealing member together with two or more traces 10 and the defective element 6 c.

(Trace 10)

Die bonding marks, wire bonding marks, die bonding material residues and/or wire residues are examples of the trace 10 that remains after removal of the defective element 6 a.

Die bonding marks and wire bonding marks are marks that indicate where a defective element was die-bonded or wire-bonded. Debris of a joining member that joins the one or more wiring patterns 4 and the light-emitting element 6, alloy layer residues with the joining member, uplift of members that are used, in the wiring pattern 4, peeling of the one or more wiring patterns 4, bonding marks and dents from wiring wires and junctions with light-emitting elements and/or ruggedness of the one or more wiring patterns 4 are examples of die bonding marks and wire bonding marks. The alloy layer residue denotes an alloy layer of solder or wiring material from ultrasound joining and wire metal or die bonding material joined to the writing pattern. Die bonding materials and wire material residues denote residues of members that are used daring die bonding and wire bonding of the defective elements.

(Reflective member 12)

A white member that contains a white filler or white powder can be used as the reflective member 12. For example, insulating resins having high reflectance, high heat resistance and high light resistance is an example of such white member. More specifically, silicone resins that contain titanium oxide, silicon oxide, barium sulfate, aluminum oxide or the like, modified types of thereof, and/or resists are examples of such white member. The reflective member 12 may contain the above-described wavelength conversion member.

As illustrated in FIG. 1C, the reflective member 12 may be used as an underfill material that is filled in under the flip-chip-mounted light-emitting element 6 f. In this case, the defective element 6 c is covered by underfill. In this case, the defective element 6 c is prevented from appearing on the surface of the substrate 2 without increasing the number of process, and it becomes possible to provide the light-emitting device 1 at a low cost.

The reflective member 12 can be provided over the entire surface of the substrate 2. In this case, it is preferable that the reflective member has functionality as resist.

The reflective member 12 can be provided between the sealing members 8 a, 8 b, 8 c, 8 d and the one or more wiring patterns 4.

[Manufacturing Method]

FIGS. 2A to 2E, 3A-3E and 4A-4E are diagrams illustrating schematic processes of a method for manufacturing a light-emitting device according to the embodiment. In the figures, FIGS. 2A-2E are plan-view diagrams, FIGS. 3A-3E are diagrams of a cross-sect ion A-A in FIGS. 2A-2E, respectively, and FIGS. 4A-4E are diagrams of a cross-section B-B in FIGS. 2A-2E, respectively.

As illustrated in FIGS. 2A to 2E, 3A-3E and 4A-4E, the manufacturing method of the light-emitting device 1 according to the embodiment has the following processes.

(First Process)

First, the substrate 2 provided with the one or more wiring patterns 4 is prepared as illustrated in FIGS. 2A, 3A and 4A.

(Second Process)

Next, the reflective member 12 is provided on the substrata 2 according to a method such as printing or the like as illustrated in FIG. 2B, 3B and 4B. The reflective member 12 has openings X at which the one or more wiring patterns 4 is/are exposed as illustrated in FIGS. 2B, 3B and 4B. The size of the area of the openings X is not particularly limited, but is preferably of a size that allows about two light-emitting elements to be mounted, so that new light-emitting elements that replace defective elements can be easily mounted.

(Third Process)

Next, as illustrated in FIGS. 2C, 3C and 4C, the plurality of light-emitting elements 6 a, 6 b, 6 c, 6 d is mounted on the one or more wiring patterns 4 that is/are provided, on the substrate 2. The light-emitting elements are ultrasonic-mounted on the one or more wiring patterns 4 in accordance with a flip-chip scheme using gold bumps.

(Fourth Process)

Next, the plurality of light-emitting elements 6 a, 6 b, 6 c, 6 d is determined to be good or detective.

(Fifth Process)

Next, as illustrated in FIGS. 2D, 3D and 4D, the new light-emitting elements 6 e, 6 f that replace the defective elements 6 a, 6 c among the plurality of light-emitting elements 6 a, 6 b, 6 c, 6 d are mounted on the same wiring pattern 4 on which the defective elements 6 a, 6 c are mounted.

The defective element 6 a is removed from the substrate 2 before or after mounting of the new light-emitting elements 6 e, 6 f . The die bonding mark, die bonding material residue or the like that, remains after removal of the defective element 6 a (for example, bump residue, alloy layer of gold and the material of the one or more wiring patterns 4) is regarded as a trace 10 that remains after removal of the defective element 6 a. The trace 10 is covered by the reflective member 12. The defective element 6 c is not removed from the substrate 2, but is covered by part of an underfill material, (example of the reflective member 12) that is filled in under the light-emitting element 6 f.

(Sixth Process)

Next, as illustrated, in FIGS. 2E, 3E and 4E, the light-emitting elements 6 e, 6 b, 6 f, 6 d are sealed by the respective sealing members 8 a, 8 b, 8 c, 8 d. The defective element 6 c and the trace 10 that remains after removal of the defective element 6 a are sealed by the same sealing members 8 a, 8 c by which the new light-emitting elements 6 e, 6 f are sealed. In the embodiment, the reflective member 12 that covers the trace 10 that remains after removal of the defective element 6 a and the reflective member 12 that covers the defective element 6 c are sealed by the same sealing members 8 a, 8 c by which the new light-emitting elements 6 e, 6 f are sealed.

An embodiment has been explained above, but the explanation relates merely to an example of the present, invention, which is in no way limited, to or by the explanation.

DENOTATION OF REFERENCE NUMERALS

-   1 light-emitting device -   2 substrate -   4 one or more wiring patterns -   6 a light-emitting element -   6 b light-emitting element -   6 c light-emitting element -   6 d light-emitting element -   6 e light-emitting element -   6 f light-emitting element -   8 a sealing member -   8 b sealing member -   8 c sealing member -   8 d sealing member -   10 trace -   12 reflective member -   X opening 

What is claim is:
 1. A light-emitting device comprising; a substrate including one or more wiring patterns provided thereon; a trace of a defective element provided on one of the one or more wiring patterns; a plurality of light-emitting elements provided on the one or more wiling patterns, wherein the plurality of tight-emitting elements includes a replacement tight-emitting element mounted on the same wiring pattern on which the trace of the defective element is provided; a reflective member covering at least a part of the trace of the defective element; and a sealing member covering the replacement light-emitting element and at least a part of the reflective member covering at least a part of the trace of the defective element.
 2. The light-emitting device according to claim 1, wherein the trace that remains after removal of the defective element is a die bonding mark and/or a die bonding material residue.
 3. The light-emitting device according to claim 1, wherein a part the reflective member is provided under at least a part of the replacement light-emitting element.
 4. The light-emitting device according to claim 1, wherein the reflective member is a white member.
 5. The light-emitting device according to claim 1, wherein the plurality of light-emitting elements is ultrasonic-mounted on the one or more wiring patterns in accordance with a flip-chip scheme.
 6. The light-emitting device according to claim 1, wherein the sealing member is selected from the group consisting of epoxy resin, silicone resin, or modified epoxy resin and modified silicone resin.
 7. The light-emitting device according to claim 1, wherein the reflective member comprises a silicone resin, a modified silicone resin or a resist containing a material selected from the group consisting of titanium oxide, silicon oxide, barium sulfate, aluminum oxide, and a wavelength conversion member.
 8. The light-emitting device according to claim 1, wherein the reflective member comprises an insulating resin containing a white filler or white powder and having a property of high reflectance.
 9. The light-emitting device according to claim 1, wherein the reflective member is disposed so that at least a part of the replacement light emitting element is exposed from the reflective member.
 10. The light-emitting device according to claim 1, wherein at least a part of a fop surface and a side surface of the replacement light emitting element is exposed from the reflective member.
 11. A method for manufacturing a light-emitting device, comprising the steps of; mounting a plurality of light-emitting elements on one or more wiring patterns on a substrate: determining that at least one of plurality of light-emitting elements is defective; and then removing the defective element of the plurality of light-emitting elements leaving a trace of the defective element on one of the one or more wiring patterns; mounting a replacement light-emitting element on the same wiring pattern on which the trace of the defective element is provided; covering at least part of the trace of the defective element with a reflective member; and sealing the replacement light-emitting element and at least a part of the reflective member covering at least a part of the trace of the defective element with a sealing member.
 12. The method for manufacturing a light-emitting device according to claim 11, wherein the trace that remains after removal of the defective element is a die bonding mark and/or a die bonding material residue.
 13. The method for manufacturing a light-emitting device according to claim 11, wherein a part the reflective member is provided under at least a part of the replacement light-emitting element.
 14. The method for manufacturing a light-emitting device according to claim 11, wherein the reflective member is a white member.
 15. The method for manufacturing a light-emitting device according to claim 11, wherein the plurality of light-emitting elements is ultrasonic-mounted on the one or more wiring patterns in accordance with a flip-chip scheme.
 16. The method for manufacturing a light-emitting device according to claim 11, wherein the sealing member is selected from the group consisting of epoxy resin, silicone resin, or modified epoxy resin and modified silicone resin.
 17. The method for manufacturing a light-emitting device according to claim 11, wherein the reflective member comprises a silicone resin, a modified silicone resin or a resist containing a material selected from the group consisting of titanium oxide, silicon oxide, barium sulfate, aluminum oxide, and a wavelength conversion member.
 18. The method for manufacturing a light-emitting device according to claim 11, wherein the reflective member comprises an insulating resin containing a white filler or white powder and having a property of high reflectance.
 19. The method for manufacturing a light-emitting device according to claim 11, wherein the reflective member is disposed so that at least a part of the replacement light emitting element is exposed from the reflective member.
 20. The method for manufacturing a light-emitting device according to claim 11, wherein at least a part of a top surface and a side surface of the replacement light emitting element is exposed from the reflective member.
 21. The method for manufacturing a light-emitting device according to claim 11, wherein the step of mounting the plurality of light-emitting elements on one or more wiling patterns on the substrate comprises providing a reflective material layer on the one or more wiring patterns on the substrate, the reflective material layer having openings exposing the one or more wiring patterns, a size of each of the openings allowing about two light-emitting elements to be mounted in each of the openings on the one or more wiring patterns on the substrate, and mounting one light-emitting element in each of the openings. 